In your trademe reference those yellow $73 ones look like the one I have. Have had no problem with it and havent used it myself but the neighbours have. Even put it on the weakest battery in neighbours motorhome and worked well. Has compressor built in to top up tyre pressures. Takes a bit of room in boot but can come in handy alright

They work ok, but like any battery powered device it goes flat when not been used, so chances are it will be flat when you really need to use it, and if it's plugged in at home charging, you will need it when you are out.

Th 600 amp one I bought just had a large UPS battery in it of dodgey quality. came with a junk transformer (so unregulated) wallwart that did about 200mA on low line voltage so would take weeks to charge. the car charger was a straight thru cable with a diode in the jumpstarter so would only charge off a running car and then really really slowly if at all.

If you have 12V in your boot, the car will keep it charged? Agree the only value in it is if you a) have it on you and b) have it charged.

I carry jumper leads and can usually find someone to jump off. I also have two cars, so at home I can jump one off the other usually :-) However I would've bought something much like the $73 ones above, had I not bought the second car.

Final point; I have AA membership, which is always handy - particularly if im driving a vehicle that's not mine, or if I lock myself out, or have another unexplained mechanical issue that's not a flat battery....

There is nothing smart in the box to control the charge, so if you were to plug it in and leave it, then it would probably slowly cook itself depending on the battery type in the car, as the calcium ones seem to need a much higher float voltage than a conventional lead acid one (measure 14.6v in a friends newish car just after starting) - no idea how the headlamps survive that.

The diode in the jumpstarter would stop it discharging back into the ignition powered line when you had the car off, but I just dont know how well the battery in it would last with that constant abuse.

Inorder to fully charge mine in a reasonable time I just hooked my hobby charger up to the giant clips and set it to a 6 cell leadacid with a 1 amp rate since it is a 10 amphour battery in it. put about 6Ah into it from new, and I have not had it discharged a great deal since then.

Really should get around to putting a ciggy lighter socket in the boot so I can leave things charging up while I am away from the car.

So really the only advantage of having the jumper kit, over jumper cables is that you don't need another car, but the downsides are that you need to have it charged before you need it, and carry it everywhere... Sounds like Jumper cables might be better.

And its gutless, no way it would start a car from a dead battery, you have to connect it to the flat battery and let it drive somewhat of a charge into it over a few mins. however it does mean you are not putting a massive draw on the running car by connecting a totally dead battery across its electrical system. Handy if you have left something on and the battery is too low to crank but still has some juice in it.

I have lost a headlight bulb from the surge when jumping another car off mine once. Its the disconnection that usually does it since the alternator is at full bore and suddenly its load is gone. So having it to offer other people vs cables is a good thing however.

networkn: I would like to think that new cars have surge protection, pretty sure I read that anything with onboard computers have something. Not sure about how the jumping car copes though.

Worst thing that should happen would be a blown fuse. Just make sure to use the manufacturers recommendations. Which are usually +ve(red) to battery, -ve(black) to chassis. Then once started disconnect the black first. Then the red second.

I have moved across the ditch. Now residing in Melbourne as a VOIP/Video Technical Trainer/Engineer.

And if you are disconnecting with the donor car running, turn on a decent amount of stuff first, some say to stop the donor before disconnecting which is what I do anyway now after losing the headlight